Stability Analysis Of Slope Based On Stress And Strain Fields

There is close relationship between stress and strain fields of slope and slope stability. How to use the stress and strain fields efficiently to identify the failure mode of slope and reinforce the slope is with important theoretical value and project sense. Starting from the aspects of theoretical analysis, test verification, numerical computation and real engineering project, the main conclusions are obtained as follows:First, deformation features of slope are studied through centrifugal model test. Tri-axial tests are conducted for soil samples to establish the variable-modulus elasto-plastic model and Et-?t double-surface model for the soil. Results by numerical methods can mainly reflect the test results before slope failure; however, the failure occurrence and it entire process need to be investigated more.Second, slope failure mode and its optimal reinforced site can be determined by the stress and strain fields of slope. The variable-modulus strength reduction method (VSRM) is adopted to compute and analyze the stress and strain fields. Numerical results shows that:in thrust load-caused slope, the stress level and the displacement of the upper region are higher than those of the lower region; while in retrogressive slope, the stress level and the displacement of the lower region are higher than those of the upper region; and the combined slope is the combination of those two failure types. Furthermore, anti-sliding piles are set at different sites of landslide to study the relationship between safety factor and the stress and strain fields of slope. It is found that setting anti-sliding piles at the site of high stress level and large displacement can lead to high safety factor. Therefore, the optimal reinforcement site is the upper region for the thrust load-caused slope, while the lower region for the retrogressive slope. As for the combined slope, the optimal reinforcement site is that of higher stress level and displacement. Similarly, it is found that better reinforcement results can be achieved if strong reinforcement is applied upon the regions with high stress and large displacement.Third, by comparing safety factors from strength reduction method (SRM) and the traditional limit equilibrium method (LEM) in different failure modes, it is found:for the thrust load-caused slope, safety factors from SRM and LEM are same, while for the retrogressive slope, safety factor from LEM is larger than that from SRM. Especially for the uneven geological condition. LEM would overrate the stability of slope.Finally, slope in different failure mode has different displacement mode. Using VSRM to analyze slope in different failure modes, it is obtained that:for the retrogressive slope, its sliding failure appears the brittle failure feature; while for the thrust load-caused slope, it would have obvious displacement before sliding, which appears the plastic failure feature. Therefore, the retrogressive mode should be avoided in slope design. It should be made the thrust load-caused mode that has obvious warning deformation before failure, like the balanced-reinforced beam, which can reduce disasters caused landslide.